Surface plasmon leakage in its coupling with an InGaN/GaN quantum well through an Ohmic contact

The authors demonstrate the leakage of surface plasmon (SP) through the Ohmic contact of either p-type or n-type GaN layer in the coupling process between SP and an InGaN/GaN quantum well (QW). It is shown that the photoluminescence (PL) intensity is significantly reduced when an Ohmic contact is formed, in contrast to the case of significant PL enhancement when an insulating thin layer is applied between the doped semiconductor and metal. The observation implies that, in using the SP-QW coupling for enhancing emission in a light-emitting diode, the metals for Ohmic contact and SP generation must be isolated from each other. A thin dielectric interlayer in the region for SP-QW coupling is useful for avoiding the leakage of SP energy. (c) 2007 American Institute of Physics.